1. Field of the Invention
The present invention relates to personal lowering devices, more particularly to lightweight portable devices having brakes for controlled descent.
2. Description of the Prior Art
Various systems have been developed for lowering persons from elevated positions in emergency situations. Fire escapes are disclosed by U.S. Pat. No. 311,039, U.S. Pat. No. 461,528, U.S. Pat. No. 1,229,394 and U.S. Pat. No. 4,063,615. Lowering devices for military use, particularly air force use, are disclosed by U.S. Pat. No. 3,159,241, U.S. Pat. No. 3,419,236 and U.S. Pat. No. 3,159,241.
Conventional devices employ rollers, pulleys, sheaves and friction brake mechanisms, often enclosed within a housing through which a rope passes. The brakes directly restrict the rope flow to control the rate of descent. The rope, therefore, is subject to stress and rapid wear. The conventional devices are bulky and uncomfortable. Those designed for military use are often suitable for use with only particular types of aircraft.
Accordingly, there is a need for a personal lowering device which is compact and lightweight so that it may be included in the personal equipment or parachute pack of an airman. There is a further need for such a device which will be usable in a variety of weather and operational conditions. Such a device should be simple to operate, requiring slight force to control the rate of descent, and durable, having parts which will resist wear.